What changed in this filing

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Item 2. Properties

2026-02-27 compared with 2025-02-28 · 26 added, 24 removed, 116 unchanged (30% of the section changed)

14 unchanged sentences

For our active and certain idled Met mining properties, Marshall Miller performs an initial assessment and based on the level of geological evidence estimates our coal resources and classifies such resources as either inferred, indicated or measured.

When considered cost beneficial by the Company, Marshall Miller further conducts a pre-feasibility study to estimate our coal reserves and classify such reserves as either proven or probable.

When we consider it cost beneficial, Marshall Miller further conducts a pre-feasibility study to estimate our coal reserves and classify such reserves as either proven or probable.

The estimates and reports prepared by Marshall Miller are reviewed by our personnel to ensure such reports have been prepared in accordance with applicable rules and regulations and that estimates are based on reasonable assumptions and reflect known facts and circumstances updated through year-end.

13 unchanged sentences

Kepler WV 36,159 20,631 15,528 209 35,950 15,996 20,163

Kingston WV 35,745 22,020 13,725 554 35,191 22,197 13,548

Kingston/Mammoth WV 33,324 19,926 13,398 555 32,769 20,120 13,204

Marfork WV 96,799 51,687 45,112 2,268 94,531 54,388 42,411

9 unchanged sentences

Kepler WV — — 5,018 31,141 — 36,159 — 39 %

Kingston WV 17,905 — 2,394 9,903 5,543 10,489 25,256 39 %

Kingston/Mammoth WV 15,329 — 3,034 9,889 5,072 11,115 22,209 37 %

Marfork WV 63,497 — 2,034 26,150 5,118 86,558 10,241 31 %

2 unchanged sentences

Total 84,873 62,967 67,784 67,180 11,682 258,455 36,031

(1) Kingston thermal reserves primarily proven and >1% sulfur;

(1) Kingston/Mammoth thermal reserves primarily proven and >1% sulfur;

Marfork and McClure/Toms Creek thermal reserves primarily probable and ≤ 1% sulfur.

2 unchanged sentences

Complex Market Pricing Per Ton (1) (2)

Kingston $211

Kingston/Mammoth $221

McClure/Toms Creek $208

3 unchanged sentences

(2) Pricing shown for primary product judgmentally selected by qualified person based on review of historical average pricing for each complexes coal products over the past 5 years.

The following is a summary of the Company’s estimated in situ inferred, indicated, and measured coal resources (exclusive of coal reserves) as of December 31, 2024 as determined by Marshall Miller:

The following is a summary of our estimated in situ inferred, indicated, and measured coal resources (exclusive of coal reserves) as of December 31, 2025 as determined by Marshall Miller:

Coal Resources (1) (Tons in thousands)

4 unchanged sentences

Kepler WV 28,471 22,950 5,521 596 27,875 17,069 11,402

Kingston WV 25,978 10,769 15,209 13,864 12,114 — 25,978

Kingston/Mammoth WV 23,472 10,206 13,266 13,864 9,608 — 23,472

Marfork WV 155,194 46,764 108,430 61,168 94,026 6,487 148,707

12 unchanged sentences

Kepler WV — — 5,363 23,108 — 26,571 1,900 48 %

Kingston WV — — 2,505 23,473 — 25,978 — 27 %

Kingston/Mammoth WV — — — 23,472 — 23,472 — 40 %

Marfork WV 103,602 — 3,650 43,799 4,143 61,450 93,744 31 %

12 unchanged sentences

Risks Factors—Risks relating to regulatory and legal developments.”

Our coal reserve and resource estimates are updated periodically to reflect coal production, acquisitions and dispositions of mineral interests, new drilling, mine or geological data, and changes in regulations, market conditions or other economic factors.

As coal seams in the United States have been mined for many years and are well established, we do not conduct material exploration activity.

3 unchanged sentences

12/31/2024 12/31/2025

Mining Complex Coal Reserves Acquired/Leased Change in Mine Plan Divested Production Coal Reserves

Mining Complex Coal Reserves Acquired/Leased Pre-Feasibility (1)

Change in Mine Plan Divested Production Coal Reserves

Aracoma 38,055 — 524 (864) — (2,595) 35,120

Kepler 38,473 — — (624) — (1,690) 36,159

Kingston 38,657 181 (1,119) — (1,974) 35,745

Kingston/Mammoth 35,745 — 978 (1,244) — (2,155) 33,324

Marfork 91,988 — 8,375 579 — (4,143) 96,799

2 unchanged sentences

Total 298,639 — 9,877 (145) — (13,885) 294,486

(1) Mineral areas subjected to pre-feasibility study in current period.

Changes in Coal Resources (Tons in thousands)

12/31/2024 12/31/2025

Mining Complex Coal Resources Initial Assessment (1)

Mining Complex Coal Resources Acquired/ Leased Pre-Feasibility (1)

Change in Mine Plan Divested Production Coal Resources

1 unchanged sentence

Kepler 30,509 — — (785) (1,253) — 28,471

Kingston 26,662 — (684) — — 25,978

Kingston/Mammoth 25,978 — (2,506) — — — 23,472

Marfork 159,694 — (3,668) (832) — — 155,194

3 unchanged sentences

Total 517,766 21,014 (10,943) (1,306) (1,253) (2,660) 522,618

(1) Mineral areas subjected to initial assessment in current year.

(1) Mineral areas subjected to pre-feasibility study in current period.

Internal Controls Disclosure

The preparation of coal reserve and resource estimates is conducted in accordance with the Company’s prescribed internal control procedures, which are designed to ensure the reliability of such estimates.

On an annual basis, Company personnel meet with the independent qualified person to provide updates to the data and assumptions to be used in performing the reserve and resource estimates.

Company personnel review the work of the qualified person to ensure such work is prepared in accordance with applicable rules and regulations and that the data and assumptions used are supportable based on historical results and current and future mine plans and reflect known facts and circumstances through the reporting date.

For example, the Company’s land personnel verify the property maps and control areas used by the qualified person based on review of underlying deed and lease records.

The Company’s engineering personnel ensure estimates are based on current mine plans, incorporate the most recent drilling and lab data, properly reflect changes in permitting status, consider known encumbrances, and are consistent with operating knowledge and expectations in terms of mining methods, recovery rates, minimum seam heights or maximum strip ratios, and saleable qualities.

The Company’s land and accounting personnel endeavor to ensure that estimates are prepared in accordance with applicable rules and regulations, that rationale for changes in estimates from prior years are reasonable and supportable, and that cash flow projections are based on reasonable and supportable assumptions with respect to forecasted production rates, coal pricing, and operating and capital costs.

The Company’s drilling, sample preparation and laboratory analysis are conducted in accordance with internal policies and procedures.

The preparation of coal reserve and resource estimates is conducted in accordance with our prescribed internal control procedures, which are designed to ensure the reliability of such estimates.

On an annual basis, our personnel meet with the independent qualified person to provide updates to the data and assumptions to be used in performing the reserve and resource estimates.

Our personnel review the work of the qualified person to ensure such work is prepared in accordance with applicable rules and regulations and that the data and assumptions used are supportable based on historical results and current and future mine plans and reflect known facts and circumstances through the reporting date.

For example, our land personnel verify the property maps and control areas used by the qualified person based on review of underlying deed and lease records.

Our engineering personnel ensure estimates are based on current mine plans, incorporate the most recent drilling and lab data, properly reflect changes in permitting status, consider known encumbrances, and are consistent with operating knowledge and expectations in terms of mining methods, recovery rates, minimum seam heights or maximum strip ratios, and saleable qualities.

Our land and accounting personnel endeavor to ensure that estimates are prepared in accordance with applicable rules and regulations, that rationale for changes in estimates from prior years are reasonable and supportable, and that cash flow projections are based on reasonable and supportable assumptions with respect to forecasted production rates, coal pricing, and operating and capital costs.

Our drilling, sample preparation and laboratory analysis are conducted in accordance with internal policies and procedures.

For example, core drilling is conducted by reputable third-party drillers and core samples are tagged.

1 unchanged sentence

Core drilling and laboratory testing results are logged into a database with restricted access.

In addition, the Company’s qualified person performs independent data verification procedures to ensure data is of sufficient quantity and reliability to reasonably support the coal reserve and resource estimates.

In addition, our qualified person performs independent data verification procedures to ensure data is of sufficient quantity and reliability to reasonably support the coal reserve and resource estimates.

Coal reserve and resource amounts are estimates and as estimates have inherent risks due to data accuracy, uncertainty from geologic interpretation, mine plan assumptions, uncontrolled property rights and permit availability, uncertainty with respect to future market supply and demand, and changes in laws and regulations.

The Company’s current coal reserves and resource estimates are based on the best information available and are subject to re-assessment when conditions change.

Our current coal reserves and resource estimates are based on the best information available and are subject to re-assessment when conditions change.

Also refer to “Item 1A.

Risk Factors for further discussion of risks associated with the estimates of the Company’s reserves and resources.

Risk Factors” for further discussion of risks associated with the estimates of our reserves and resources.

The following map shows the locations of our material mining properties and corporate headquarters:

Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 2. Properties